<!-- Licensed under a BSD license. See license.html for license -->
<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
    <title>WebGL - 3D Step 2 - Use 3D Geometry</title>
    <link type="text/css" href="../resources/webgl-tutorials.css" rel="stylesheet" />
</head>

<body>
    <div id="info">
        <div class="description">
            Drag sliders to translate, rotate, and scale.
        </div>
        <a href="https://webglfundamentals.org/webgl/lessons/zh_cn/webgl-3d-orthographic.html" target="_blank">WebGL
            三维正射投影</a>
    </div>
    <canvas id="canvas"></canvas>
    <div id="uiContainer">
        <div id="ui">
            <div id="x"></div>
            <div id="y"></div>
            <div id="z"></div>
            <div id="angleX"></div>
            <div id="angleY"></div>
            <div id="angleZ"></div>
            <div id="scaleX"></div>
            <div id="scaleY"></div>
            <div id="scaleZ"></div>
        </div>
    </div>
</body>
<!-- vertex shader -->
<script id="3d-vertex-shader" type="x-shader/x-vertex">
attribute vec4 a_position;

uniform mat4 u_matrix;

void main() {
    // Multiply the position by the matrix.
    gl_Position = u_matrix * a_position;
}
</script>
<!-- fragment shader -->
<script id="3d-fragment-shader" type="x-shader/x-fragment">
precision mediump float;

uniform vec4 u_color;

void main() {
    gl_FragColor = u_color;
}
</script>
<!--
for most samples webgl-utils only provides shader compiling/linking and
canvas resizing because why clutter the examples with code that's the same in every sample.
See http://webglfundamentals.org/webgl/lessons/webgl-boilerplate.html
and http://webglfundamentals.org/webgl/lessons/webgl-resizing-the-canvas.html
for webgl-utils, m3, m4, and webgl-lessons-ui.
-->
<script src="../resources/webgl-utils.js"></script>
<script src="../resources/webgl-lessons-ui.js"></script>
<script>
    "use strict";

    function main() {
        // Get A WebGL context
        /** @type {HTMLCanvasElement} */
        var canvas = document.getElementById("canvas");
        var gl = canvas.getContext("webgl");
        if (!gl) {
            return;
        }

        // setup GLSL program
        var program = webglUtils.createProgramFromScripts(gl, ["3d-vertex-shader", "3d-fragment-shader"]);

        // look up where the vertex data needs to go.
        var positionLocation = gl.getAttribLocation(program, "a_position");

        // lookup uniforms
        var colorLocation = gl.getUniformLocation(program, "u_color");
        var matrixLocation = gl.getUniformLocation(program, "u_matrix");

        // Create a buffer to put positions in
        var positionBuffer = gl.createBuffer();
        // Bind it to ARRAY_BUFFER (think of it as ARRAY_BUFFER = positionBuffer)
        gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
        // Put geometry data into buffer
        setGeometry(gl);

        function radToDeg(r) {
            return r * 180 / Math.PI;
        }

        function degToRad(d) {
            return d * Math.PI / 180;
        }

        var translation = [45, 150, 0];
        var rotation = [degToRad(40), degToRad(25), degToRad(325)];
        var scale = [1, 1, 1];
        var color = [Math.random(), Math.random(), Math.random(), 1];

        drawScene();

        // Setup a ui.
        webglLessonsUI.setupSlider("#x", { value: translation[0], slide: updatePosition(0), max: gl.canvas.width });
        webglLessonsUI.setupSlider("#y", { value: translation[1], slide: updatePosition(1), max: gl.canvas.height });
        webglLessonsUI.setupSlider("#z", { value: translation[2], slide: updatePosition(2), max: gl.canvas.height });
        webglLessonsUI.setupSlider("#angleX", { value: radToDeg(rotation[0]), slide: updateRotation(0), max: 360 });
        webglLessonsUI.setupSlider("#angleY", { value: radToDeg(rotation[1]), slide: updateRotation(1), max: 360 });
        webglLessonsUI.setupSlider("#angleZ", { value: radToDeg(rotation[2]), slide: updateRotation(2), max: 360 });
        webglLessonsUI.setupSlider("#scaleX", { value: scale[0], slide: updateScale(0), min: -5, max: 5, step: 0.01, precision: 2 });
        webglLessonsUI.setupSlider("#scaleY", { value: scale[1], slide: updateScale(1), min: -5, max: 5, step: 0.01, precision: 2 });
        webglLessonsUI.setupSlider("#scaleZ", { value: scale[2], slide: updateScale(2), min: -5, max: 5, step: 0.01, precision: 2 });

        function updatePosition(index) {
            return function (event, ui) {
                translation[index] = ui.value;
                drawScene();
            };
        }

        function updateRotation(index) {
            return function (event, ui) {
                var angleInDegrees = ui.value;
                var angleInRadians = angleInDegrees * Math.PI / 180;
                rotation[index] = angleInRadians;
                drawScene();
            };
        }

        function updateScale(index) {
            return function (event, ui) {
                scale[index] = ui.value;
                drawScene();
            };
        }

        // Draw the scene.
        function drawScene() {
            webglUtils.resizeCanvasToDisplaySize(gl.canvas);

            // Tell WebGL how to convert from clip space to pixels
            gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);

            // Clear the canvas.
            gl.clear(gl.COLOR_BUFFER_BIT);

            // Tell it to use our program (pair of shaders)
            gl.useProgram(program);

            // Turn on the attribute
            gl.enableVertexAttribArray(positionLocation);

            // Bind the position buffer.
            gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);

            // Tell the attribute how to get data out of positionBuffer (ARRAY_BUFFER)
            var size = 3;          // 3 components per iteration
            var type = gl.FLOAT;   // the data is 32bit floats
            var normalize = false; // don't normalize the data
            var stride = 0;        // 0 = move forward size * sizeof(type) each iteration to get the next position
            var offset = 0;        // start at the beginning of the buffer
            gl.vertexAttribPointer(
                positionLocation, size, type, normalize, stride, offset);

            // set the color
            gl.uniform4fv(colorLocation, color);

            // Compute the matrices
            var matrix = m4.projection(gl.canvas.clientWidth, gl.canvas.clientHeight, 400);
            matrix = m4.translate(matrix, translation[0], translation[1], translation[2]);
            matrix = m4.xRotate(matrix, rotation[0]);
            matrix = m4.yRotate(matrix, rotation[1]);
            matrix = m4.zRotate(matrix, rotation[2]);
            matrix = m4.scale(matrix, scale[0], scale[1], scale[2]);

            // Set the matrix.
            gl.uniformMatrix4fv(matrixLocation, false, matrix);

            // 绘制几何体
            var primitiveType = gl.TRIANGLES;
            var offset = 0;
            var count = 16 * 6;
            gl.drawArrays(primitiveType, offset, count);
        }
    }

    var m4 = {

        projection: function (width, height, depth) {
            // Note: This matrix flips the Y axis so 0 is at the top.
            return [
                2 / width, 0, 0, 0,
                0, -2 / height, 0, 0,
                0, 0, 2 / depth, 0,
                -1, 1, 0, 1,
            ];
        },

        multiply: function (a, b) {
            var a00 = a[0 * 4 + 0];
            var a01 = a[0 * 4 + 1];
            var a02 = a[0 * 4 + 2];
            var a03 = a[0 * 4 + 3];
            var a10 = a[1 * 4 + 0];
            var a11 = a[1 * 4 + 1];
            var a12 = a[1 * 4 + 2];
            var a13 = a[1 * 4 + 3];
            var a20 = a[2 * 4 + 0];
            var a21 = a[2 * 4 + 1];
            var a22 = a[2 * 4 + 2];
            var a23 = a[2 * 4 + 3];
            var a30 = a[3 * 4 + 0];
            var a31 = a[3 * 4 + 1];
            var a32 = a[3 * 4 + 2];
            var a33 = a[3 * 4 + 3];
            var b00 = b[0 * 4 + 0];
            var b01 = b[0 * 4 + 1];
            var b02 = b[0 * 4 + 2];
            var b03 = b[0 * 4 + 3];
            var b10 = b[1 * 4 + 0];
            var b11 = b[1 * 4 + 1];
            var b12 = b[1 * 4 + 2];
            var b13 = b[1 * 4 + 3];
            var b20 = b[2 * 4 + 0];
            var b21 = b[2 * 4 + 1];
            var b22 = b[2 * 4 + 2];
            var b23 = b[2 * 4 + 3];
            var b30 = b[3 * 4 + 0];
            var b31 = b[3 * 4 + 1];
            var b32 = b[3 * 4 + 2];
            var b33 = b[3 * 4 + 3];
            return [
                b00 * a00 + b01 * a10 + b02 * a20 + b03 * a30,
                b00 * a01 + b01 * a11 + b02 * a21 + b03 * a31,
                b00 * a02 + b01 * a12 + b02 * a22 + b03 * a32,
                b00 * a03 + b01 * a13 + b02 * a23 + b03 * a33,
                b10 * a00 + b11 * a10 + b12 * a20 + b13 * a30,
                b10 * a01 + b11 * a11 + b12 * a21 + b13 * a31,
                b10 * a02 + b11 * a12 + b12 * a22 + b13 * a32,
                b10 * a03 + b11 * a13 + b12 * a23 + b13 * a33,
                b20 * a00 + b21 * a10 + b22 * a20 + b23 * a30,
                b20 * a01 + b21 * a11 + b22 * a21 + b23 * a31,
                b20 * a02 + b21 * a12 + b22 * a22 + b23 * a32,
                b20 * a03 + b21 * a13 + b22 * a23 + b23 * a33,
                b30 * a00 + b31 * a10 + b32 * a20 + b33 * a30,
                b30 * a01 + b31 * a11 + b32 * a21 + b33 * a31,
                b30 * a02 + b31 * a12 + b32 * a22 + b33 * a32,
                b30 * a03 + b31 * a13 + b32 * a23 + b33 * a33,
            ];
        },

        translation: function (tx, ty, tz) {
            return [
                1, 0, 0, 0,
                0, 1, 0, 0,
                0, 0, 1, 0,
                tx, ty, tz, 1,
            ];
        },

        xRotation: function (angleInRadians) {
            var c = Math.cos(angleInRadians);
            var s = Math.sin(angleInRadians);

            return [
                1, 0, 0, 0,
                0, c, s, 0,
                0, -s, c, 0,
                0, 0, 0, 1,
            ];
        },

        yRotation: function (angleInRadians) {
            var c = Math.cos(angleInRadians);
            var s = Math.sin(angleInRadians);

            return [
                c, 0, -s, 0,
                0, 1, 0, 0,
                s, 0, c, 0,
                0, 0, 0, 1,
            ];
        },

        zRotation: function (angleInRadians) {
            var c = Math.cos(angleInRadians);
            var s = Math.sin(angleInRadians);

            return [
                c, s, 0, 0,
                -s, c, 0, 0,
                0, 0, 1, 0,
                0, 0, 0, 1,
            ];
        },

        scaling: function (sx, sy, sz) {
            return [
                sx, 0, 0, 0,
                0, sy, 0, 0,
                0, 0, sz, 0,
                0, 0, 0, 1,
            ];
        },

        translate: function (m, tx, ty, tz) {
            return m4.multiply(m, m4.translation(tx, ty, tz));
        },

        xRotate: function (m, angleInRadians) {
            return m4.multiply(m, m4.xRotation(angleInRadians));
        },

        yRotate: function (m, angleInRadians) {
            return m4.multiply(m, m4.yRotation(angleInRadians));
        },

        zRotate: function (m, angleInRadians) {
            return m4.multiply(m, m4.zRotation(angleInRadians));
        },

        scale: function (m, sx, sy, sz) {
            return m4.multiply(m, m4.scaling(sx, sy, sz));
        },

    };

    // Fill the buffer with the values that define a letter 'F'.
    function setGeometry(gl) {
        gl.bufferData(
            gl.ARRAY_BUFFER,
            new Float32Array([
                // left column front
                0, 0, 0,
                30, 0, 0,
                0, 150, 0,
                0, 150, 0,
                30, 0, 0,
                30, 150, 0,

                // top rung front
                30, 0, 0,
                100, 0, 0,
                30, 30, 0,
                30, 30, 0,
                100, 0, 0,
                100, 30, 0,

                // middle rung front
                30, 60, 0,
                67, 60, 0,
                30, 90, 0,
                30, 90, 0,
                67, 60, 0,
                67, 90, 0,

                // left column back
                0, 0, 30,
                30, 0, 30,
                0, 150, 30,
                0, 150, 30,
                30, 0, 30,
                30, 150, 30,

                // top rung back
                30, 0, 30,
                100, 0, 30,
                30, 30, 30,
                30, 30, 30,
                100, 0, 30,
                100, 30, 30,

                // middle rung back
                30, 60, 30,
                67, 60, 30,
                30, 90, 30,
                30, 90, 30,
                67, 60, 30,
                67, 90, 30,

                // top
                0, 0, 0,
                100, 0, 0,
                100, 0, 30,
                0, 0, 0,
                100, 0, 30,
                0, 0, 30,

                // top rung right
                100, 0, 0,
                100, 30, 0,
                100, 30, 30,
                100, 0, 0,
                100, 30, 30,
                100, 0, 30,

                // under top rung
                30, 30, 0,
                30, 30, 30,
                100, 30, 30,
                30, 30, 0,
                100, 30, 30,
                100, 30, 0,

                // between top rung and middle
                30, 30, 0,
                30, 30, 30,
                30, 60, 30,
                30, 30, 0,
                30, 60, 30,
                30, 60, 0,

                // top of middle rung
                30, 60, 0,
                30, 60, 30,
                67, 60, 30,
                30, 60, 0,
                67, 60, 30,
                67, 60, 0,

                // right of middle rung
                67, 60, 0,
                67, 60, 30,
                67, 90, 30,
                67, 60, 0,
                67, 90, 30,
                67, 90, 0,

                // bottom of middle rung.
                30, 90, 0,
                30, 90, 30,
                67, 90, 30,
                30, 90, 0,
                67, 90, 30,
                67, 90, 0,

                // right of bottom
                30, 90, 0,
                30, 90, 30,
                30, 150, 30,
                30, 90, 0,
                30, 150, 30,
                30, 150, 0,

                // bottom
                0, 150, 0,
                0, 150, 30,
                30, 150, 30,
                0, 150, 0,
                30, 150, 30,
                30, 150, 0,

                // left side
                0, 0, 0,
                0, 0, 30,
                0, 150, 30,
                0, 0, 0,
                0, 150, 30,
                0, 150, 0]),
            gl.STATIC_DRAW);
    }

    main();
</script>

</html>